Srivastava, S CGupta, R R1980-07-012009-05-271980-07-012009-05-271980-07-01Srivastava SC, Gupta RR. Direct-reading normograms for systolic time intervals (S.T.I.). Indian Heart Journal. 1980 Jul-Aug; 32(4): 257-60http://imsear.searo.who.int/handle/123456789/4167engAdolescentAdultAgedFemaleHeart RateHumansMaleMiddle AgedMyocardial ContractionSystoleDirect-reading normograms for systolic time intervals (S.T.I.).Journal Article